The burglary happened at about 8.30pm on Tuesday, November 27 at the dealership's unit at the New York Mills industrial estate at Summerbridge near Harrogate.
The burglars drove to the site in a long wheel base panel van.
They used a power saw to break in and put 15 high-value mountain bikes, most worth between Â£3,000 and Â£5,000 each, into the van.
The van drove off the site and four of the burglars left the area on foot.
Police have released a photo of one of the most distinctive of the stolen bikes.
Anyone with information can emial [email protected] or call 101, quoting reference 12180221536.